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Post by kyrillB. on Apr 1, 2023 9:03:16 GMT -8
Hi there, and thanks for your wonderful thoughts. Please share any posts that I missed, that could help me for my questions. I couldn't find all answers because reading English isn't my best skill. For Clarification: I my focus is an oven that stores heat in a bench. That is the main focus. This oven is made for my Yurt without any heat storing mass in itself. I life in Germany so we sometimes get around 10 degrees minus in Winter.
Requirements:
- Not too heavy but enough mass for the heat storage, because there are no walls of stone that can storage heat. - I will burn Lots of thin brunches, because as I am a Arborist I get those for free. - 10 cm base so 13,82 riser - 55cm depth - ISA 4,5 square meters (not jet exactly in the drawings) - a bypass will be half way up from the first bell to the chimney. - the walls of the first bell are withe a expansion joint. The bench without. -The materials are: Shamotte/ fireclay brick, Calciumsilikat plates or vermiculite, normal bricks. -The top of my first Bell should be warm enough for cooking?!
My first questions: How will the draft be? How can I improve the draft? How big must the third port between the first bell and the second bench bell be? How big should the chimney be? Next questions:- how will small brunches influence the combustion? - did I calculated enough insulation downwards? - to what do I have to pay attention using Vermiculite plates or Calciumsilikat plates or CF? What are the differences for my oven? |
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Post by peterberg on Apr 3, 2023 10:54:26 GMT -8
Requirements:
- Not too heavy but enough mass for the heat storage, because there are no walls of stone that can storage heat. In order to get enough mass for heat storage the thing will be heavy, no escaping from that. Using a bench will spread out the weight, though. - I will burn Lots of thin brunches, because as I am a Arborist I get those for free. - 10 cm base so 13,82 riser - 55cm depth - ISA 4,5 square meters (not jet exactly in the drawings) - a bypass will be half way up from the first bell to the chimney. - the walls of the first bell are withe a expansion joint. The bench without. -The materials are: Shamotte/ fireclay brick, Calciumsilikat plates or vermiculite, normal bricks. -The top of my first Bell should be warm enough for cooking?! Yes, but you'll need a cast iron or glass ceramic cooktop for this. My first questions: How will the draft be? Good, given the fact that you want to employ a bypass. How can I improve the draft? A chimney that is high enough and of sufficient diameter is a requirement. How big must the third port between the first bell and the second bench bell be? This left me a bit puzzled, but now I think you mean the opening between bell and bench. Answer: as high and wide as the inside of the bench itself. How big should the chimney be? [/div][/quote] At least 4 meters high and 150 mm diameter. Don't try to be skimpy on that and use 130 mm diameter because of the cost. This will work against you and every week or month you have to fight the heater because it won't draw. Next questions:- how will small brunches influence the combustion? Not a great deal, probably it will burn quite agressive. But then: as long as it is woody stuff and dry, it will burn like hell. You'll need a certain amount of kilograms in order to extract enough power so refilling will be in order. - did I calculated enough insulation downwards? In case you mean under the firebox - to what do I have to pay attention using Vermiculite plates or Calciumsilikat plates or CF? What are the differences for my oven? I'd think you have to specify where you want to use which plate and for what purpose. |
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Post by kyrillB. on Apr 8, 2023 12:33:11 GMT -8
- I made the pass between bell and bench bigger. - I added more mass, instead of insulation. - The top of the bell will be Iron or glass with a big water pot on top, or a additional firebrick plate for heat storage.
- I still could not decide whether I use Vermiculite or Calciumsilikat for insulation. I first want to find out which has a longer durability. I will read more first.
Questions - Did I understand it right that Fire brick and insulation is not glued together but hold together by a frame? If I make a frame around the DSR with iron that extend much more than my bricks, they will push each other apart. But I also need a frame for the oven door and to hold everything together. Can somebody give me note how to hold everything together, without the iron moving problem?
- I found different qualities of Fire bricks. A30t A35t A40t for different temperatures. Which one do I need? is A30t enough?
- How big must the gap between the bottom and the chimney be so that enough air is sucked in?
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Post by peterberg on Apr 9, 2023 3:37:32 GMT -8
Did I understand it right that Fire brick and insulation is not glued together but hold together by a frame? Yes, that could be by means of a frame, since the insulation is a rigid plate. If I make a frame around the DSR with iron that extend much more than my bricks, they will push each other apart. But I also need a frame for the oven door and to hold everything together. Can somebody give me note how to hold everything together, without the iron moving problem? Please, don't overthink the whole thing. Making a frame around the core and insulation would mean the bricks might extend as quick as the steel, since this is separated from the bricks by insulation. Moreover, both aluminum silicate and vermiculite are not as rigid as bricks, far from that. There won't be a problem except in your head in my opinion. I found different qualities of Fire bricks. A30t A35t A40t for different temperatures. Which one do I need? is A30t enough? I think you are referring to the numbers on the bricks, which are almost certain insulating firebricks. Using it in the firebox isn't a terrific idea, those bricks are prone to abrasion by the fuel. I would recommend the higest number, that's the sturdiest of those three. - How big must the gap between the bottom and the chimney be so that enough air is sucked in? First: the pipe need to be clear all around so the gases are able to enter from all sides. Mounting the pipe flat against the side wall of the bench would mean about a quarter of the circumference is blocked off, in a corner about half. Second: the pipe need to be the same diameter as the system size, or larger. In practise, the pipe size would be 150 mm as being closest to the system size. Please don't think the slightly smaller one of 130 mm would be enough, it won't. Third: the space under the pipe is an imaginary ring, this should be ay least 200% of the csa of the pipe itself. The pipe's csa is 177 cm², 200% of that is 354 cm², devided by the pipe's circumference would be 7.5 cm, being half of the pipe's diameter. Since this is the bare minimum, I would recommend to extend this to 10 cm at least. Having the wall of the bench close by, the active part of the circumference would be down from 47 cm to slightly more than 35 cm. Having done the calculation, it turns out the minimum distance would be 10 cm, so one quarter up like the example above would be... 12.5 cm for this case. |
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Post by kyrillB. on Apr 29, 2023 3:39:30 GMT -8
Thanks again. I am thankful for all help.
Updates:
-I will make a frame around the DSR. -I found some fire bricks plates made out of more than 60 percent Al2O3. Maybe I use Bauxite... SiO2 is always quite low. heat conductivity is between: 1,9 to 2,7 W/mk depending which stone I choose.
Questions: -I am searching for a affordable cast iron cook top. Help is very welcome. size 96cm x 74cm, a bit smaller works too!
- How high/thick must the bench lid be, I need a guess for Dimensions. I have already 8 cm Sandstone slab, and I wonder If I place beneath it normal brick layer? -I now decided to insulate the oven with 1000 °C Calciumsilicat plates. (Are they Recommendable or avoidable? ) but for the riser I am unsure if Calciumsilicat are good enough and lasting long enough... What are recommendation? Vermiculite withe a impregnation(Which?) ? ( I hesitate using Vermiculite, because I am not sure if the insulating factor is high enough and the durability is long enough) With CF I am not sure for my black oven and food that could be baked there...
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Post by kyrillB. on May 11, 2023 2:58:23 GMT -8
I designed a different secondary air system for the DSR2. I have no pre experience, but I want to get in touch with each other about it. The only reason why I changed Peter van den Berg design (which i highly appreciate) is, that I don't want to rebuild the iron p-channel each year.(And I cant too) I am curious for all your experience and Ideas.
The secondary air is running through the roof of my burning chamber and in the one proposal it ends in the top of the port. In the second proposal it ends on the downsides of the Port. greetings
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Post by peterberg on May 11, 2023 8:15:16 GMT -8
Where it ends at the top is correct. The side of the firebox should be somewhat lower as compared to the riser side. The effect is the lowest pressure is exactly there where the air enters the port. Cross section area of the entire p-channel should be 5% of system size.
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Post by kyrillB. on May 11, 2023 9:54:54 GMT -8
Oh great! so I will try that.Cross section area will be 5 %. But I am a bit confused. So you write that the variation with one air duct is working, right?! Wouldn't the variation with tow secondary air channels work better than the other, because the air enters at the bottom?(If I change the port on the riser side slightly bigger)
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Post by peterberg on May 13, 2023 6:50:23 GMT -8
Oh great! so I will try that.Cross section area will be 5 %. But I am a bit confused. So you write that the variation with one air duct is working, right?! Wouldn't the variation with tow secondary air channels work better than the other, because the air enters at the bottom?(If I change the port on the riser side slightly bigger) The air entering at the bottom is utterly wrong, been there, done that. However, side air in the port should enter in the top half, not lower. And the feed coming over the top of the firebox should be much wider. Although both configurations are looking quite similar they aren't, at all. Better to use the simplest one, has been used for many years now and works guaranteed. All possible combinations has been tried and tested, just a few has stood the test. There's a Dutch saying: better well copied than poorly invented yourself. |
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Post by kyrillB. on May 13, 2023 7:48:33 GMT -8
Yes that makes sense. I Changed everything:https://app.sketchup.com/share/tc/europe/wdpHxs33ehQ?stoken=yhM_eHUC750t1_ejrK0XbHfo3RpG2-nA-sKNRgfNmMK40Kvalqh1yseCXiYV7gqo&source=web
Could you Peter or somebody else send me threads/drawing/sketch up files of those combinations that stood the test? I would like to follow your saying and copy those configurations that have become established.
thanks in advance!
Martin
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Post by kyrillB. on May 29, 2023 10:07:04 GMT -8
Dear BBR/DSR2-Bilders, dear Peter,
as Peter says "better well copied than poorly invented yourself" I searched for "simplest one, has been used for many years now and works guaranteed" P-Channel made by bricks, in this forum but without success. Maybe because English is not my mother tongue. So again I ask for help to find the threads posts and drawings of a secondary air supply without iron, that "stood the test"
Thank in advance for anybody helping! greetings!
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Post by kyrillB. on Jan 2, 2024 9:07:04 GMT -8
Hi again,
I made new plans. BBR 10,32(because of the stone size)
Last Summer we build up the Yurt and at the end I postponed the oven project because I had no capacity left. Also I realized that my plan doesn't fit in the Yurt. It was way too big. So now I have a new plan and I have already some silimanit stones and oven doors, so I am collecting everything for the summer! In front of the stove are the planed materials: Vermeculite, Silimanite, Shamotte, Firebrick, ceramic fiber cardboard, natural slate, brick, wood, cast iron, The stove has a 3 meter chimney as i draw in the sketchup. On top of the Bell, will come a square water container.
I rad super much threads with so much helpful information thanks to all of you.
Still I have some Questions:
1. I drew the ISA of my bell to big. Instead of 2,5 m I have 2,87. Will that work, because I have A bypass?
2, Are there any experience suggestions to make the white oven better work?
3. I am wondering if the chimney of 15cm is to big for the small stove, or will it just have a good draft withe this chimney?
I would be glad to get some help! Also if you find other weak points! best new year greetings kyrill
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Post by peterberg on Jan 3, 2024 2:58:16 GMT -8
Why building such a tiny heater? On the same footprint a larger one like 120 or 130 mm would fit nicely.
#1 Yes, it will work because of the bypass.
#2 Insulation material between the bricks and the oven walls and top.
#3 Yes, 150 mm chimney for such a tiny stove is far too big. In fact, its cross section area is 2.25 times larger than required.
The air inlet you've drawn is feeding the floor channel only. When the door is closed the fire will turn very sooty and dies.
Could you please upload the file to another website and provide a link? Preferably saved in SKP 8 format but SKP 17 would do as well for me. The benefit is that I would be able to take the thing apart and take measurements.
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Post by kyrillB. on Jan 3, 2024 7:45:48 GMT -8
I hope this link works. Sadly it will be delated after a week. But I can send it again if needed.
Thank you peter for your replay.
I planed a bigger version, with a 13,82 riser. It is in the sketchup file next to the Yurt-floor. I am not sure in my decision. I changed it to a smaller BBR because of the foundation of the floor of the whole Yurt. I could ad more foundation, but I am afraid the Floor it self could collapse from the weight. That made me plane smaller. Now we have a normal stove with 8 kW. That is quite good, but without a long thermal store. I could use the 13,82 version with a small bell...
Yes the air inlet is missing. I will ad it during the construction.
Now that I already have a 150mm chimney, is there a possibility to still use it? For example make the inlet on the ground smaller? At the top of the chimney it is 120mm wide, to have a better draft!
thanks for your help!
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Post by peterberg on Jan 4, 2024 7:55:41 GMT -8
Ok, I've seen the drawing, looks correct to me. The floor of your yurt might not be able to support the entire load. Best to cut out a piece of the floor and cast a concrete slab on solid grade underneath.
What is the reason you want a bench? Using the same footprint a single bell could be placed there. A bit higher bell maybe, and quite somewhat wider. If you want to sit against the heater, no problem. Just a small wooden bench and that's it. Simpler to build as well.
Your system would be almost 140 mm, that will work very nice together with that 150 mm chimney. The part that necks down to 120 mm has to be removed, it'll give better draft with high end temperatures. But this heater won't exhaust high temperatures, it will be hampered this way. Unless: you are going to build a 120 mm system.
To make things simpler: skip the octagon riser and use thin firebricks to build a square one. Works as well, insulation can be wrapped around and kept in place with chicken wire.
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